Various types of heat pumps for transferring heat are well known and have been in common use for many years. Refrigeration and heating systems utilizing motor-driven compressors are common examples of systems for pumping relatively large amounts of heat, but, of course, they require external pumping power. Heat pipes have had more limited use in recent years and have the advantage that they do not require active heating or external pumping power, but they have the disadvantage that their construction requires relatively complex technology.
U.S. Pat. No. 4,148,195 to Gerstmann et al. describes a liquid piston Stirling-type heat pump, and this patent contains a discussion of other prior art in this area. A problem with the heat pump covered by this patent is that it requires active heating by a fuel burner for operation, and the overall construction and operation are relatively complex.
It is a general object of the present invention to provide a passive fluid piston heat pump that is relatively efficient in operation and is relatively uncomplicated in construction.